1. Field of the Invention
The present invention relates to deformation of ceramic materials, and more particularly to superplastic deformation of zirconia ceramic materials.
2. Description of Related Art
Ceramic materials, such as zirconia (ZrO.sub.2) ceramic materials, have gained increased attention in recent years as an important material for many commercial applications. Growing numbers of ceramic material applications in the aerospace automotive and tool and die industries, for example, have increased the need for materials producers to fabricate improved ceramic materials. Manufacturing methods such as stretching, bending, bulging, extruding, or forging of sheet or bar stock materials have been employed to manufacture such ceramic materials. Unfortunately, absent special measures, such methods tend to result in relatively low yields of useful ceramic articles.
Superplastic deformation methods have been employed in connection with many metallic materials to fabricate useful articles. By "superplastic deformation", as used herein, is meant the relatively extensive deformation (e.g. greater than about 50% in compression or elongation) of a material at a relatively low stress under a relatively high strain rate. Until the present invention, however, superplastic deformation methods used to fabricate ceramic materials, such as zirconia ceramic materials, have required relatively extreme operating conditions. That is, relatively high deformation temperatures, or relatively low strain rates have typically been required in order to deform zirconia compounds under a given stress. From a commercial standpoint, however, such operating ranges tend to render superplastic deformation methods impractical as used with ceramic materials, such as zirconia ceramic materials.